This invention relates to a shoe sole for athletic shoes with an outsole and a midsole of volume-compressible foamed material, as well as air cushions provided in the midsole.
A shoe sole for athletic shoes with a damping midsole is known, for example, from U.S. Pat. No. 4,486,964. In this previously known athletic shoe sole, four damping parts that are approximately round in an unweighted condition and contain air or gas, are placed next to one another with practically no distance between them in the heel area of the midsole. These parts are jointly sheathed by the foam material of the midsole; but, the spatial extension of these damping parts cannot be seen in detail. A disadvantage of this known embodiment of a shoe sole for athletic shoes is that the air/gas damping parts used there easily wear out and their restoring force is also insufficient.
U.S. Pat. No. 1,559,532 discloses a midsole or intermediate sole wherein the intermediate sole has soft (unfoamed rubber or other waterproof material), cellular projecting portions, one set at the sole and one set at the heel. The outer sole has box-like recesses, which correspond with and closely fit over the projecting cellular or resilient portions, which may be in the form of right-angular criss-cross webs in recticular fashion. On the other hand, when resilient projecting parts are provided on the intermediate sole which consist of sponge (foamed) rubber, a cellular structure with wide or extensive cells is not disclosed as being used. However, in either case, the resilient structures are formed as depending projections at the underside of the body of the intermediate sole that must be received in chambers formed in the outsole in order to create air cushions, and no provision is made for enabling the resilient or cellular structures to be viewable.
Soles having a window through which the midsole is viewable are known (see U.S. Pat. Nos. 4,481,727 and 4,694,591). However, these constructions are not used with honeycomb midsoles and the midsoles of these patents are intended to defect downwardly through the window opening into contact with the ground under the force of impacts.